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2004 Crf 250r starts easy when cold but not when hot

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I have a 2004 crf 250r it starts super easy when cold (like 2 kicks). But when its hot it is hard to start. I’ve found it easier to just wait for it to cool down. What is happening here? And how can I fix this? Thanks

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On 9/29/2020 at 1:21 AM, motrock93b said:

Have you tried using the hot start lever?

When I bought the bike it didn’t have a cable hooked up to the lever so I’ve never used. Ive tried to see where it would have hooked up but I couldn’t find a place. So I assumed it didn’t come stock with one but I may be wrong.

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23 minutes ago, Dallin Zeyer said:

Where would you look in order to hook the compression release up?

The compression release is automatic, and part of the cam setup. 
 

The hot start is the opposite of the choke. It leans the mixture. One thing you could try is to very, very slowly slightly open Your throttle and hold it steady. Then try to start it. Keep the throttle slightly opened, and don’t let it move or your accelerator pump may squirt fuel into the carburetor. This will lean it out a bit, similar to pulling the little hot start lever by your left grip. 

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On 10/6/2020 at 8:51 PM, duCOD pro said:

Have you had your valves checked recently? That can cause issues with irregular starting behavior.

Ya they are good and at spec. 

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On 10/6/2020 at 9:14 PM, motrock93b said:

The compression release is automatic, and part of the cam setup. 
 

The hot start is the opposite of the choke. It leans the mixture. One thing you could try is to very, very slowly slightly open Your throttle and hold it steady. Then try to start it. Keep the throttle slightly opened, and don’t let it move or your accelerator pump may squirt fuel into the carburetor. This will lean it out a bit, similar to pulling the little hot start lever by your left grip. 

Ok thanks. So just barely open the throttle?

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Yes. And hold it. Do not let the throttle move, or the accelerator pump will squirt fuel into the carburetor intake creating a rich condition. Open the throttle very slowly to that slightly open point for the same reason. If you’re having no luck, you can try opening the throttle fully. Hold it there as you try to start your bike. This is basically the procedure used when your bike is flooded. The idea is to create a lean condition as you try to start a hot engine, which is the opposite idea for a cold engine. Be ready to immediately close the throttle once the bike starts!
 

Good luck, and let us know how it works out!

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Couple days late on this, but if the OP wants to spend $32...

Number 4 on Honda handle lever/switch/cable schematic, and number 8 on carburetor schematic.  

 

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In the picture, the black plastic "u" shaped thing right above the choke.  That is the connector housing that holds the hot start plunger in the carb. Cable goes from lever on handle bar, under gas tank and into this housing.  

Take your seat and tank off to run the cable...The hot start plunger/housing just screws into side off carb...If you use a crows foot wrench, or even a long pair off needle nose pliers, you can unscrew it without removing the carb.  once you get the old one off it will be self explanatory how to pull the plunger out of the housing and insert the cable. 

At rocky mountain atv/mc I think the hot start set is $19 and the cable $13.  Look up oem parts for your bike

20201013_144417.jpg

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4 hours ago, tenntim said:

In the picture, the black plastic "u" shaped thing right above the choke.  That is the connector housing that holds the hot start plunger in the carb. Cable goes from lever on handle bar, under gas tank and into this housing.  

Take your seat and tank off to run the cable...The hot start plunger/housing just screws into side off carb...If you use a crows foot wrench, or even a long pair off needle nose pliers, you can unscrew it without removing the carb.  once you get the old one off it will be self explanatory how to pull the plunger out of the housing and insert the cable. 

At rocky mountain atv/mc I think the hot start set is $19 and the cable $13.  Look up oem parts for your bike

20201013_144417.jpg

Ya so I’ve got that u shaped tube but at the end of it there is a screw in it. So I’ll just have to buy a cable. Unscrew that tube that is already on there and screw the new one in where the old one came from?

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Yes, the black piece attached to the carb is the "hot start set".  Where it attaches to the carb, it has a plastic hex fitting that you turn with a wrench or other grasping tool and the unit unthreads from the carb.  The hex end (attached to carb) will spin freely on the u shaped body, allowing it to thread on or off without twisting the cable.  When you have it removed there is a brass plunger and spring inside it.  

In the picture...the cable goes into the end that is pointing up, (cable coming down from under gas tank).  remove the plunger and spring from the "set", insert cable into "set", run cable through spring and attach to plunger.  then pull attached cable, spring and plunger back into the body of the hot start set and thread the assembly onto body of carb.  Run your cable under tank and up to handlebar and attach to hot start lever.

When you say there is a screw in the end of it, you have me thinking that someone inserted a screw into the cable end of the hot start set?  where the cable would normally enter.  If so, when you remove the assembly from carb body...check for the plunger and spring to come out with it.  since you have no cable, the plunger may be stuck in the orifice when you remove the body.  if so, it will be visible and you just grab it out with needle nose pliers or tweezers.  

If it was me, I would replace the set along with your new cable, and not use the old one that is currently on your carb.  The spring may be messed up, and the plunger may be stuck slightly from non use.  the components may be missing entirely. If the plunger doesnt slide right out easily, clean the orifice with a bit of wd-40 to get any corrosion off before you install new assembly.  Anytime your bike sits for awhile without running, reach over and squeeze the hot start lever once or twice just to keep that plunger freely moving so it doesnt stick in there.

Seriously though, when you have the new cable and "hot start set" assembly sitting in front of you it will be really obvious how it all goes together.  And it is amazing how well it works if you stall out and go to immediately restart a hot engine.  just remember to release that lever quickly when it starts.  That lean condition make starting hot engine a lot easier, but it will kill the engine from a lean bog just as quickly when its running!  Let us know how it goes!

 

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On 9/13/2020 at 11:23 AM, Dallin Zeyer said:

I have a 2004 crf 250r it starts super easy when cold (like 2 kicks). But when its hot it is hard to start. I’ve found it easier to just wait for it to cool down. What is happening here? And how can I fix this? Thanks

Have you tried posting in the right forum?

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I debated whether to say this or not, but in the interest of injecting a little humor into the discussion....No, he did not pose the question in the Honda crf250r and x subforum.  However, he did receive two equally good options to solve his problem.  One would work well with no cost, and one would work well with just a little cost, but they both work.  He is now awaiting parts to correct his problem and everyone is happy. 

So I guess you could say that yes, in a sense, he did post in the "right" forum. Lol 

  • Haha 2

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Sorry it took so long. But I installed the hot start last night. I will be testing it out one of these weekends when I go riding again. 

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